Nickel base alloys represent an important class of commercial alloys which are commonly used in applications where good mechanical properties are important, such as high temperature strength and corrosion resistance. The art has long sought and continues to actively seek new and improved nickel base alloys where the properties of high temperature strength and corrosion resistance are improved, together with improvement of other mechanical properties such as hot workability, creep resistance and high creep rupture strength.
Typical nickel alloys such as Monel (70% by weight nickel, 30% by weight copper) are found to be highly susceptible to high temperature corrosin known as oxidation when exposed to high temperature gases containing oxygen. The mechanism of the oxidation attack is an intergranular one and the affected alloys often crumble apart. It is obviously highly desirable to provide improved nickel base alloys having good oxidation resistance as well as high temperature strength and corrosion resistance.
In accordance with U.S. Pat. No. 3,810,754 a series of oxidation resistant nickel base alloys are provided. It is desirable to maintain the oxidation resistance of this family of alloys while providing still further improvements in mechanical properties such as hot tensile strength, creep resistance and high creep rupture strength.